1. Field of the Invention
The present invention is directed to a computed tomography apparatus of the type for conducting a spiral scan (sometimes referred to as a spiral-helical scan) of an examination volume.
2. Description of the Prior Art
The technique of spiral scanning of a volume is acquiring increasing significance in the field of computed tomography. For this purpose, an exposure unit, composed of an x-ray source (x-radiator) and a radiation detector are mounted on a gantry or scan-frame, and the gantry or frame is rotated through an angle larger than 360.degree. while the patient support is moved in a longitudinal direction through the scanned measurement field. Such a spiral scan computed tomography apparatus is disclosed, for example, in the U.S. Pat. No. 5,291,402.